1. Field of the Invention
The present invention relates to a head support mechanism provided in a magnetic disk apparatus for use in a computer storage apparatus and the like. More particularly, the present invention relates to an optimal head support mechanism for high-density data recording, and a thin film piezoelectric actuator suitable for the head support mechanism.
2. Description of the Related Art
Recently, the recording density of a magnetic disk provided in a magnetic disk apparatus has been vigorously increased. A magnetic head for use in recording and reproducing data to and from a magnetic disk is typically provided on a slider. The slider carrying the magnetic head is supported on a head support mechanism provided in a magnetic disk apparatus. The head support mechanism has a head actuator arm to which the slider is attached. The head actuator arm is rotated by a voice coil motor (VCM). The head provided on the slider is placed at an arbitrary position on a magnetic disk by controlling the voice coil motor.
High-density data recording on a magnetic disk requires a high level of precise positioning of the magnetic head. In the case where the positioning of the magnetic head is performed by the VCM rotating the head actuator arm, there is a problem in that the positioning of the magnetic head is less precise. To avoid such a problem, a head support mechanism has already been proposed which achieves high-precision positioning of the magnetic head.
FIG. 45 is a top view illustrating a conventional head support mechanism 400 for use in a magnetic disk apparatus. A head 402 is used to record and reproduce data to and from a rotating magnetic disk (not shown). The head 402 is supported on an end portion of a suspension arm 404. The other end portion of the suspension arm 404 is supported on a projection portion 408 provided in the tip portion of a carriage 406 in such a manner as to rotate within a small angle range on the projection portion 408. A base portion of the carriage 406 is supported on an axis member 410 fixed to a housing of the magnetic disk apparatus in such a manner as to rotate on the axis member 410.
A permanent magnet (not shown) is fixed to the carriage 406. A drive coil 414 as a part of a magnetic circuit 412 fixed to the housing is controlled by an excitation current flowing therethrough. The carriage 406 is rotated on the axis member 410 by interaction of the permanent magnet and the drive coil 414. Thereby, the head 402 is moved in a substantially radial direction of a magnetic disk.
A pair of piezoelectric elements 416 are provided between the carriage 406 and the suspension arm 404. The longitudinal directions of the piezoelectric elements 416 are slightly deviated from the longitudinal direction of the carriage 406 in opposite directions. The suspension arm 404 is rotated within a small angular range on the projection portion 408 and along a surface of the carriage 406 by expansion or contraction along a direction indicated by arrow A14 of the piezoelectric elements 416. Thereby, the head 402 attached to the tip portion of the suspension arm 404 is moved along a surface of a magnetic disk within a small range so that the head 402 can be precisely placed at a desired position on the magnetic disk.
In the conventional head support mechanism 400 of FIG. 45, each piezoelectric element 416 is interposed between the suspension arm 404 and the carriage 406. Side portions in the longitudinal direction of each piezoelectric element 416 contact the suspension arm 404 and the carriage 406. Deformation of each piezoelectric element 416 causes the suspension arm 404 to be rotated so that the head 402 is slightly displaced. In other words, a voltage is applied to each piezoelectric element 416 to cause the rotation of the suspension arm 404, resulting in a small displacement of the head 402. However, the head 402 does not always follow the voltage applied to each piezoelectric element 416 with great precision. It is thus unlikely that the head 402 is precisely placed at a desired position.